Angulating Bone Plate

ABSTRACT

An angulating spinal plate assembly for fixation and/or support of bones of the spinal column is provided. The angulating bone plate includes interleaved, arcuate sheets that facilitate relative motion between first/second elements. An implant assembly is also provided that includes an angulating bone plate and associated first/second intervertebral plates that extend therefrom. The angulating bone plate generally includes an interleaved elements, e.g., an upstanding tab that cooperates with opposing faces of an opening, that permit rotational movement as between first/second implant elements until a desired relative orientation is achieved. At such time, a fixation/locking element is generally employed to fix the first/second implant elements relative to each other. The rotational movement permitted is generally in multiple planes based on the cooperative arcuate surfaces provided in the disclosed elements, i.e., side-to-side and top-to-bottom freedoms of movement.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority benefit to a provisional patentapplication which is entitled “Angulating Bone Plate,” which was filedon Nov. 24, 2014, and assigned Ser. No. 62/083,763. The entire contentof the foregoing provisional patent application is incorporated hereinby reference.

BACKGROUND

1. Technical Field

The present disclosure relates to devices and systems for fixationand/or support of bones. In particular, the present disclosure relatesto a spinal plate assembly for fixation and/or support of bones of thespinal column. The plate of the present disclosure has particularapplication in situations where the surgical goal is to fuse one or morespinal levels.

2. Background Art

Spinal plates are commonly used and there are many versions in the priorart. Prior art spinal plates generally consist of one or more structuralelements that are connected to each of the vertebral bodies adjacent tothe level(s) to be fused via screws passing through holes in thestructural elements and into the vertebral bodies. Some type of lockingmechanism is generally provided to prevent or resist screw migrationback through the structural elements. Spinal plates can be used forfusions throughout the spine.

In some instances, there may be a benefit to adjust the lordosis of thesegment. One way to achieve that adjustment is via an adjustableinterbody fusion device, such as that described by U.S. Pat. No.8,007,536 to Christensen. The contents of the Christensen '536 patentare incorporated herein by reference. When adjusting the lordosis of theinterbody device, there may also be a benefit to have a similaradjustment in the spinal plates.

The present disclosure relates to spinal plates that accommodate a rangeof lordosis and then can be locked in a selected lordosis position.

SUMMARY

According to the present disclosure, an advantageous spinal plate isprovided. Exemplary spinal plates according to the present disclosuregenerally include two inter-related structural elements. In an assembledposition, the two elements mate to form a plate. In combination, theplate has mounting features, e.g., at least two holes to permit bonescrews or other fasteners to penetrate the structural elements andengage vertebral bodies, e.g., adjacent to the disc to be fused. Ingeneral, the two elements are permitted to move relative to each otherunless and until a locking feature is engaged, which locks the twoelements relative to each other. The locking feature is generallyreleasable, i.e., it is possible to “reverse” the locking function ifdesired.

The present disclosure further provides an implant assembly thatincludes an angulating bone plate and associated first/secondintervertebral plates that extend therefrom. The angulating bone plategenerally includes an interleaved elements, e.g., an upstanding tab thatcooperates with opposing faces of an opening, that permit rotationalmovement as between first/second implant elements until a desiredrelative orientation is achieved. At such time, a fixation/lockingelement is generally employed to fix the first/second implant elementsrelative to each other. The rotational movement permitted is generallyin multiple planes based on the cooperative arcuate surfaces provided inthe disclosed elements, i.e., side-to-side and top-to-bottom freedoms ofmovement.

Additional features, functions and advantages associated with thedisclosed spinal plate will be apparent from the detailed descriptionwhich follows, particularly when read in conjunction with the appendedfigures.

BRIEF DESCRIPTION OF DRAWINGS

To assist those of skill in the art in better understanding how to makeand use the disclosed spinal plate, reference is made to theaccompanying figures, wherein:

FIG. 1 is an oblique view of an exemplary spinal plate according to thepresent disclosure;

FIG. 2 is an oblique view of an exemplary bottom element of thedisclosed spinal plate;

FIG. 3 is an oblique view of an exemplary top element of the disclosedspinal plate;

FIG. 4 is a right section view of an exemplary spinal plate according tothe present disclosure;

FIG. 5 is a right section view of an exemplary top element of thedisclosed spinal plate;

FIG. 6 is right section view of an exemplary bottom element of thedisclosed spinal plate;

FIG. 7 is a top view of an exemplary bottom element of the disclosedspinal plate;

FIG. 8 is an oblique back view of an alternate exemplary embodiment ofthe disclosed spinal plate;

FIG. 9 is an oblique view of an exemplary bone plate and inter-bodydevice in an assembled configuration according to the presentdisclosure;

FIG. 10 is a side view of the assembled, exemplary bone plate andinter-body device shown in FIG. 9;

FIG. 11 is an oblique view of an exemplary superior implant element thatmay be assembled with an inferior implant element to define a bone plateand inter-body device according to the present disclosure;

FIG. 12 is a top view of the exemplary superior implant element shown inFIG. 11;

FIG. 13 is an oblique view of an exemplary inferior implant element thatmay be assembled with a superior implant element to define a bone plateand inter-body device according to the present disclosure;

FIG. 14 is a side view of the exemplary inferior implant element shownin FIG. 13; and

FIG. 15 is a top view of the assembled, exemplary bone plate andinter-body device of FIGS. 8-14.

DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

In exemplary embodiments of the present disclosure, an advantageousspinal plate is provided. With initial reference to FIGS. 1-7, exemplaryspinal plates according to the present disclosure include twointer-related structural elements. In an assembled position (FIG. 1),the two elements (1,2) mate to form a plate. In combination, the platehas at least two holes (3) to permit bone screws or other fasteners topenetrate the structural elements and engage vertebral bodies, e.g.,adjacent to the disc to be fused. In general, the two elements arepermitted to move relative to each other unless and until a lockingfeature is engaged, which locks the two elements relative to each other.The locking feature is generally detachable or reversible, such that thetwo elements may be allowed to again move relative to each other, as maybe desirable in a clinical application, and then re-locked relative toeach other (on multiple occasions).

For clarity of description, the two elements are referenced as “top” and“bottom”—these designations reference relative positioning of the twoelements based on a patient's spinal anatomy, but it is to be understoodthat the “top” element could be the “bottom” element (and vice versa)without departing from the spirit or scope of the present disclosure.Similarly, in different anatomical applications, the top/bottomrelationship may instead be a side-to-side relationship, as will beapparent to persons skilled in the art.

As shown in FIGS. 2 and 3 (showing respectively exemplary bottom and topelements), the mating is via a series of interacting sheets (21, 22, 23,24, 31, 32, 33) that extend towards each other from the screw receivingportions of the elements (25, 35). The sheets of the bottom element (21,22, 23, 24) may be aligned with spacings or channels defined between thesheets of the top element (31, 32, 33) to enable mating and sliding ofthe top element relative to the bottom element. Each sheet defines agenerally planar or arcuate geometry that further defines two generallyopposing faces. When mated, one or more “bottom sheets”, e.g., sheet 22,is sandwiched between and is in confronting relation with opposed facesof two “top sheets”, e.g., sheets 31, 32. Similarly, one or more “topsheets”, e.g., sheet 32, is positioned between and is in confrontingrelation with opposed faces of two “bottom sheets”, e.g., sheets 22, 23.Thus, mating of elements 1, 2 generally involves an interleaving ofcooperative sheets associated therewith. However, it is to be noted thata single interleaving of sheets may be effective to achieve the desiredclinical results of the present disclosure, in which case a single sheetis positioned between and is in confronting relation with opposed facesof two other sheets.

As shown in FIGS. 4-6, it is preferable that all of the sheets (21, 22,23, 24, 31, 32, 33) have faces that are or are defined by (in whole orin part) arcs (51, 52, 53, 54, 55, 56, 61, 62, 63, 64, 65, 66) sharing acommon center. This arcuate geometry ensures that the relative movementof one element (1) to the other element (2) is consistent with arotation about the common center. This “rotational” movement of thefirst element relative to the second element is to be contrasted with“planar translation” (i.e., side-by-side linear translation), and such“rotational” movement advantageously facilitates spinal alignment duringclinical procedures. Thereafter, once locked in place, the disclosedbone plate—in combination with an implant—is effective to establish adesired spinal alignment.

When the disclosed plate is created in a configuration as describedabove and applied to the anterior aspect of a spinal segment (i.e.,vertebral body, disc, vertebral body) via screws or other fasteners,movement of one element relative to the other will allow aflexion/extension movement of the spine, without significant distractionor compression of the spinal segment. This relative movement of theelements (1, 2) may be beneficial in enabling proper alignment of thespine for the fusion procedure, which has been shown to be beneficial tooutcomes.

To provide stability to a treated segment, the two elements (1, 2) mustbe locked relative to each other. In exemplary embodiments of thepresent disclosure, the means to lock the two elements together isenabled by features structurally associated with both elements. As shownin FIG. 2, an exemplary locking feature includes a fastener (26) thatextends in a generally front to back direction relative to the bottomelement (2). As shown in FIG. 6, the fastener is connected to, or anintegral part of, the back-most sheet (24). Each of the sheets closer tothe front (21, 22, 23) have aligned holes to permit the fastener to passthrough.

On the top element (1), each of the exemplary sheets (31, 32, 33) has aslot 36. The slot enables the fastener (26) to pass through the sheet,even when the top element (1) is shifted relative to the bottom element(2).

To lock the top element (1) relative to the bottom element (2), a nut(not shown) or functionally similar structure is applied to thefront-most aspect (27) of the fastener (26). In implementations that usea nut, the fastener (26) is generally threaded along at least thefront-most aspect (27) of its length. A variety of other fasteners couldbe used according to the present disclosure, including clamps, clips,pins, or similar fastening structures. As the fastener is tightened, acompressive force is applied across each of the sheets. Using astructural material, such as stainless steel or a commonly used medicalimplant material, such as a titanium alloy, a significant friction forceis generated at each face of each sheet. The plate could also befabricated (in whole or in part) using structural plastics, such as PEEKor UHMWPE, but these polymeric materials are less preferred as they tendto have lower coefficients of frictions when coupled with themselvesthan the metals commonly used in medical implants.

By having multiple sheets, the frictional force, which maintains theposition of the two elements (1, 2) when locked, is also multiplied,providing greater stability. For this reason, there may be advantages tohave a greater number of sheets for the given dimensions of the plate,although effective results are achievable with fewer sheets. Indeed,there can be as few as one sheet extending from the top element, and asfew as two sheets extending from the bottom element (or vice versa), buta greater number of inter-leaved sheets may be preferred (assumingclinical space to accommodate the plate's dimension) for thestability/frictional force attributes noted above.

As described above, the sheets are generally curved in at least oneplane, as shown in FIGS. 4-6. In the plane perpendicular to the arcs(51, 52, 53, 54, 55, 56, 61, 62, 63, 64, 65, 66), the sheets may be flator curved. FIG. 7 shows the sheets curved in the perpendicular plane.The benefit of this configuration is that it imparts greater bendingstiffness to each of the individual sheets and also resists translationsand rotations of the top element with respect to the bottom element indirections other than intended.

When the angulating bone plate of the present disclosure is coupled witha disc implant, such as a disc implant of the type described byChristensen in U.S. Pat. No. 8,007,536, a surgical procedure can bedescribed where the segment lordosis is adjusted intraoperatively, andthen fixed in a particular location.

The surgical procedure would generally be performed as follows:

-   -   1. The disc space is approached in a standard fashion (e.g.,        anteriorly, laterally or posteriorly, as well as the        intermediate positions, such as TLIF or transforaminal).    -   2. The disc is partially evacuated in the standard fashion.    -   3. The endplates are prepared in the standard fashion, removing        the cartilage.    -   4. A trial implant is placed in the disc space to determine the        appropriately sized implant.    -   5. An implant, e.g., an implant of the type described by        Christensen in U.S. Pat. No. 8,007,536, is implanted in the disc        space.    -   6. A plate fabricated according to the current disclosure is        applied adjacent to the implant.    -   7. The spinal segment is positioned to set the correct amount of        lordosis. This can be done in a variety of means, including        moving portions of the table that the patient is resting on, or        placing additional padding in certain locations between the        patient and the bed, or by other means such as an inflatable        balloon placed between the patient and the bed prior to surgery,        and then partially inflated during surgery to induce the correct        amount of lordosis.    -   8. Once the lordosis is satisfactory, the plate of the current        disclosure is locked in position using the fastener/fastening        mechanism.

Of note, the positioning/locking steps can be repeated, if desired,i.e., by first releasing the fastener/fastening mechanism, resetting theamount of lordosis, and then re-locking the disclosed plate to fix theadjusted amount of lordosis.

Alternatively, a plate of the current disclosure may be fabricated witha geometry that is adapted to engage the implant, e.g., an implant ofthe typed disclosed by Christensen in U.S. Pat. No. 8,007,536, so thatthe plate and implant can be pre-assembled and applied in a single step,as opposed to two steps (i.e., steps 5 and 6 above).

FIG. 8 shows an alternate exemplary embodiment of the presentdisclosure. In the alternative embodiment of FIG. 8, the plate isfabricated with a geometry that is adapted to engage an implant. Inparticular, FIG. 8 shows a top element (81) and a bottom element (82).Sheets of the top element (83, 84, 85) and sheets of the bottom element(86, 87, 88, 89) are shown in a fully aligned/interleaved position.Towards the back of the assembled spinal plate, there may be one or morefeatures that facilitate engagement with an implant.

As shown in FIG. 8, the exemplary embodiment includes both surfaces andfasteners that facilitate engagement with an implant. For example,surfaces 90 and 92 of the top and bottom elements, respectively, may beadvantageously shaped to engage the front of the implant. Likewise,depending on the design of the implant, one or more fasteners (91, 93)may be provided as a means to connect the disclosed plate relative to animplant. A variety of fasteners could be used for this purpose,including threaded connectors, as well as a variety of clamps, clips,pins or similar fastening structures.

It is generally preferable that both the top element (81) and the bottomelement (82) include faces at the extreme back of the plate, such thatboth the top and bottom elements are adapted to engage differentcomponents of an implant. This design feature enables both insertion ofthe assembled plate and implant, and an ability to manipulate both theplate and the implant simultaneously when adjusting rotation in situ(e.g., by extending or collapsing the top and bottom elements relativeto each other).

Turning to FIGS. 9-15, a further exemplary implementation of the presentdisclosure is depicted and described herein. Specifically, FIGS. 9, 10and 15 show an exemplary bone plate and inter-body device 100 thatincludes a superior implant element 102 (FIGS. 11 and 12) and aninferior implant element 104 (FIGS. 13 and 14). The bone plate andinter-body device 100—referenced as “implant assembly 100”hereafter—provides first/second elements that integrally combine thestructures associated with an angulating bone plate and the structuresassociated with an inter-body device or implant. The inter-bodydevice/implant aspects of the disclosed implant assembly 100 may beadvantageously based on the teachings of U.S. Pat. No. 8,906,095 toChristensen et al., the content of which is incorporated herein byreference in its entirety.

Of note, the terms “inferior” and “superior” are used for convenience ofdescription. However, it is to be understood throughout this disclosurethat the “inferior implant element” may be positioned inferior orsuperior to the “superior implant element”, and that the “superiorimplant element” may be positioned inferior or superior to the “inferiorimplant element”. Thus, the terms “inferior” and “superior” areequivalent to “first” and “second” implant elements for purposes ofimplementation of the present disclosure, i.e., the features/functionsmay be implemented interchangeably according to the present disclosure.

As shown in FIGS. 9-15, the superior implant element 102 includes anupstanding flange 106 that defines a first hole 108 for use in mountingsuperior implant element 102 relative to vertebral bodies, e.g., using abone screw or other fastener (not shown), and a second hole/opening 110that facilitates fixation/locking of superior implant element 102relative to inferior implant element 104. The interior of hole/opening110 may be advantageously threaded to facilitate the notedfixation/locking functionality using a threaded screw/fastener (notshown). In addition, threading of the interior of hole/opening 110permits withdrawal of a threaded screw/fastener advanced therethrough,thereby permitting “unlocking” of superior implant element 102/inferiorimplant element 104, as may be clinically desired in connection withpositioning/implantation of implant assembly 100.

Upstanding flange 106 generally defines an arcuate/semi-circular topface 112 and an arcuate/semi-circular bottom face 114. Thearcuate/semi-circular bottom face 114 is generally inwardly steppedrelative to the side faces 116, 118 of upstanding flange 106, therebydefining first and second ledge faces 120, 122 on either side ofarcuate/semi-circular bottom face 114.

First and second ledge faces 120, 122 are adapted to engage opposedregions of inferior implant element 104 (see FIG. 9), while thearcuate/semi-circular bottom face 114 extends into and cooperates with acorresponding arcuate/semi-circular recess defined by interior implantelement 104 (as described below). A first intervertebral element 124extends from upstanding flange 106 and defines first and second openings126, 128. Features and functions of first intervertebral element 124 aredescribed in greater detail below and with reference to U.S. Pat. No.8,906,095, previously incorporated herein by reference.

Turning to the inferior implant element 104, it is noted that suchelement includes a flange portion 130 that defines a pair of spacedholes/openings 132, 134 for use in fixing the inferior implant element104 relative to vertebral bodies, e.g., using bone screws or otherfasteners (not shown). Flange portion 130 also defines anarcuate/semi-circular recess 136 (best seen in FIG. 13) that isconfigured to receive and cooperate with arcuate/semi-circular bottomface 114 of superior implant element 102. The interacting arcuate facesof upstanding flange 106 and flange portion 130 permit rotational motionas between the superior and inferior implant elements 102, 104. Thedegree of rotational motion is limited by the abutting interaction offirst and second ledge faces 120, 122 defined by upstanding flange 106and the opposed upper faces 138, 140 defined on either side ofarcuate/semi-circular recess 136 of flange portion 130. The geometriesof the ledge faces 120, 122 and upper faces 138, 140 may be formed so asto accommodate a desired level of rotational freedom between first andsecond implant elements 102, 104, as will be apparent to persons skilledin the art based on the disclosure herein. Of note, the ledge faces 120,122 and the upper faces 138, 140 can be used with an extendinginstrument to induce lordosis of the segment. Indeed, clinicalinteraction with one or more of these surfaces/faces provides analternate method for inducing lordosis (see step 7 in the surgicalprocedure outlined above).

A second intervertebral element 142 extends from flange portion 130 anddefines first and second openings 144, 146. Features and functions ofsecond intervertebral element 142 are described in greater detail belowand with reference to U.S. Pat. No. 8,906,095, previously incorporatedherein by reference.

The first and second openings associated with each of the firstinter-vertebral element 124 and the second intervertebral element 142encompass a substantial portion of the surface areas of the opposedfaces thereof, e.g., greater than 50% of such surface areas. In thisway, bone in-growth into implant assembly 100 so as to “fix” first andsecond intervertebral elements 124, 142 relative to each other isencouraged. However, it is to be understood that the present disclosureis not limited by or to implementations wherein the openings constituteopenings at the noted level. For example, the openings may constitute alesser percentage of the surface area, e.g., on the order of 10%, or anintermediate level, e.g., between 10% and 50%. Still further, theopenings may constitute a greater percentage of the surface area, e.g.,greater than 50%. It is further noted that bone in-growth may beachieved in exemplary embodiments without the provision of openings inthe surface area, e.g., wherein fusion occurs through bone growth atleast in part anterior to the first and second inter-vertebral elements.

With reference to FIG. 11, superior implant element 102 defines abounded opening 148 that is nested between the first and second openings126, 128 of the first intervertebral element 124 and substantiallycentered on the central axis of the first intervertebral element 124. Afirst boundary wall 150 of bounded opening 148 defines an arcuatesurface and functions as a first “sheet” for purposes of interleavedinteraction of superior and inferior implant elements 102, 104,according to the present disclosure. The opposed boundary wall 152 maybe defined by or in proximity to an interior face of the upstandingflange 106, and such opposed boundary wall 152 functions as a second“sheet” for purposes of interleaved interaction of superior and inferiorimplant elements 102, 104, according to the present disclosure.

Turning to FIGS. 13 and 14, the inferior implant element 104 defines anupstanding tab 154 that is configured and dimensioned to pass intobounded opening 148 of the superior implant element 102. Upstanding tab154 defines arcuate opposed faces 156, 158 that cooperate withcorresponding radiused boundary walls 150, 152 of bounded opening 148 topermit limited axial rotational movement as between superior andinferior implant elements 102, 104. Thus, upstanding tab 154 functionsas a further “sheet” according to the present disclosure, the upstandingtab 154 being configured and dimensioned to be interleaved betweenopposed sheets defined by the superior implant element 102, i.e.,boundary walls 150, 152 thereof.

As shown in FIG. 14, upstanding tab 154 defines arcuate surfaces 156,158. This further radiused geometry associated with upstanding tab 154and the opposed boundary walls 150, 152 of the superior implant element102 permits a further rotational degree of freedom as between thesuperior and inferior implant elements 102, 104. In particular,repositioning of the superior and inferior elements 102, 104 is possiblebased on flexion/extension rotational freedom of movement which areaccommodated by the interleaved upstanding tab 154 and cooperatingboundary walls 150, 152. A small amount of lateral bending rotation,i.e., rotation about an anterior-to-posterior axis, may also beaccommodated thereby.

Once the desired relative positioning of superior and inferior implantelements 102, 104 is achieved clinically, the implant elements 102, 104may be fixed/locked relative to each other by advancing a lockingelement (not pictured) through threaded hole/opening 110 to engage face158 of upstanding tab 154. Repositioning is permitted by reversing thedirection of the locking element to disengage from face 158, and thenretightening once the desired relative orientation is achieved.

With further reference to FIG. 14, it is noted that flange portion 130defines an angled/arcuate downward extension relative to a horizontalplane defined by second intervertebral element 142. This angled/arcuategeometry facilitates positioning of the inferior implant device 104relative to surrounding anatomical structures.

As described in greater detail in U.S. Pat. No. 8,906,095 (incorporatedherein by reference), the outer profiles of the first and secondinter-vertebral elements 124, 142 are the same (or substantially thesame) such that, when coupled/assembled, a substantially uniform outeredge/profile is defined. Thus, the combined/assembled profiles of thefirst and second inter-vertebral elements of implant assembly 100 definean anterior edge and a posterior edge. The anterior edge may be brokeninto three (3) sub-regions for description purposes: two anterolateraledges that surround a central anterior edge. Recessed geometryassociated with anterolateral edges relative to the central edge mayallow placement of bone materials and/or other desired materialsanterior to implant assembly 100 in a location that may facilitateand/or induce bone fusion. This recessed region adjacent theanterolateral edges may also advantageously accommodateplacement/coupling of fusion blocks. The outer profiles of the first andsecond inter-vertebral elements 124, 142 may also be broken into tworegions, where the plate portion (106) is not central, but is insteadanterolateral, with the remainder of the anterior edge recessed.

With reference to the coupling of exemplary implant assembly 100, it isnoted that the first and second inter-vertebral elements 124, 142 definecooperative inner faces that facilitate relative movement therebetweenfor an initial period of time post-implantation of implant assembly 100.Thus, the inner face of first intervertebral element 124 defines acentral region and two wing regions. The central region and wing regiontogether form or bound opening 126, whereas the central region and theother wing region form or bound opening 128.

The inner face of second intervertebral element 142 also defines acentral region and two wing regions. The central region and first wingregion together form or bound opening 144, whereas the central regionand the other wing region form or bound opening 146.

The first and second inter-vertebral elements 124, 142 of implantassembly 100 are advantageously movably coupled with respect to eachother when the inner face of first inter-vertebral element 124 isbrought into abutting engagement with the inner face of secondinter-vertebral element 142. When brought into the noted abuttingengagement, opening 126 of first inter-vertebral element 124substantially aligns with opening 144 of second inter-vertebral element142, and opening 128 of first inter-vertebral element 124 substantiallyaligns with opening 146 of second inter-vertebral element 142. Stillfurther, the central region of first inter-vertebral element 124 is inabutting relationship with the central region of second inter-vertebralelement 142 to define an articulating region therebetween (see FIG. 6 ofU.S. Pat. No. 8,906,095, incorporated herein by reference).

Generally, the articulating region provides primary contact between thefirst and second inter-vertebral elements 124, 142. The openings 126,128 formed in wing regions of the first inter-vertebral element 124 andthe openings 144, 146 formed in wing regions of the secondinter-vertebral element 142 may receive bone materials (or othermaterials) to facilitate bone in-growth therethrough. In addition,interaction/contact between the respective wing regions of the first andsecond inter-vertebral elements 124, 142 advantageously function tolimit lateral bending therebetween. In exemplary embodiments of thepresent disclosure, implant assembly 100 is symmetric (or substantiallysymmetric) about an anterior-posterior plane, i.e., along the planedefined by the articulating region.

The central region of the first inter-vertebral element 124 is generallydefined as a swept surface with a first profile in the medial lateraldirection and a second profile in the anterior-posterior direction. Itis generally preferable that the first profile in the medial-lateraldirection be a single arc. It is also generally preferable that theprofile in the anterior-posterior direction be composed of a line withan arc, wherein the line is tangent to the arc and arc is posterior.This arc combination advantageously allows for normal anatomical motionof a patient in flexion-extension, while controlling contact forcesbetween the first and second inter-vertebral elements 124, 142. However,the present disclosure is not limited by or to the arc-basedimplementations described herein.

The central region of the second inter-vertebral element 142 is alsogenerally defined as a swept surface with a first profile in the mediallateral direction and a second profile in the anterior posteriordirection. It is generally preferable that the first profile be a singlearc. It is also generally preferable that the second profile be composedof a line. However, as with the first inter-vertebral element 124, thepresent disclosure is not limited by or to the arc-based implementationsdescribed herein.

So as to reduce contact stresses, it is generally preferable that theradii of the mating arcs in the medial lateral direction be of similar(but not the same) value, thereby reducing the contact stress betweenthe first and second inter-vertebral elements 124, 142. Also, the extentof the profile of the first inter-vertebral element 124 is generallygreater than the second inter-vertebral element 142 to enable/facilitaterotation of the second inter-vertebral element 142 relative to the firstinter-vertebral element 124.

There is also an advantageous relationship between the profiles in theanterior-posterior direction of exemplary first and secondinter-vertebral elements 124, 142 of the present disclosure. Forexample, the anterior-posterior profile of the first inter-vertebralelement 124 is typically matched with the anterior-posterior profile ofthe second inter-vertebral element 142. This matching ofanterior-posterior profiles enables the necessary and/or desiredflexion-extension motion of a patient and facilitates positionaladaptability of the disclosed disc implant in an initial periodpost-implantation. Of note, the central regions of first and secondinter-vertebral elements 124, 142 define a contact region in the alignedposition. It is also noted that as between the medial-lateral profilesand the anterior-posterior profiles, the anterior-posterior curves aregenerally not as closely matched.

While exemplary profiles have been described with reference to implantassembly 100, a variety of alternate profiles are contemplated. Forexample, medial lateral profiles may be formed/defined by geometriesthat include radiused opposing faces, elliptical opposing faces,spline-shaped opposing faces or other generally curved elements.Similarly, the anterior-posterior profiles may be formed/defined bygeometries that include radiused opposing faces, elliptical opposingfaces, spline-shaped opposing faces or other generally curved elements.It is further contemplated that the articulating geometries may bereversed/inverted, such that the disclosed geometric features andfunctions of the first inter-vertebral element 124 described herein maybe associated instead with second inter-vertebral element 142, and viceversa. Thus, the geometric features/functions of profiles may be traded.However, it is noted that a reversal of the profile features describedherein may not be preferable because the center of rotation of the firstand second inter-vertebral elements 124, 142 would be potentiallyshifted away from the natural center of rotation of the spine segment,which is believed to be in the posterior half of the lower body of thespine segment. Also, there is a benefit of a relationship (alignment)between interbody and plate. That is, the centers of the radii definingthe sheets of the plate should be positioned appropriately relative tothe anterior-posterior profiles.

As described herein, exemplary disc implant assemblies according to thepresent disclosure are adapted for clinical insertion between vertebratebodies. The implant generally comprises two elements, which are coupledtogether forming the disc implant. The opposing surfaces of the twoelements are described as internal coupling surfaces and may includefeatures/cooperative mechanisms that advantageously function to movablycouple the elements relative to each other upon initial implantation ofthe disclosed spinal implant. Thus, the coupling means/mechanism mayserve to connect and/or align the first and second inter vertebralelements relative to each other. Coupling of the inter-vertebralelements may regulate movement of the first and second inter-vertebralelements relative to each other, i.e., prior to fixation of the firstand second inter-vertebral elements relative to each other based on bonein-growth. Thus, coupling of the two inter-vertebral elements does notfixedly position the elements relative to each other. Minor movements ofthe elements relative to each other in at least one direction aregenerally permitted when said elements are coupled according to thepresent disclosure.

A third element may be advantageously positioned between the first andsecond elements described herein. Thus, for example, a non-metalcomponent may be positioned between the first and second elements so asto be positioned between contact regions thereof. The non-metalcomponent may be fabricated from a polymeric material, e.g.,polyethylene, polyether ketone ketone (PEKK) and/or polyether etherketone (PEEK). The non-metal component may take the form of a sheet,relatively thin block or surface treatment, and advantageously functionsto prevent metal-to-metal contact, thereby reducing the potential formetal failure. Indeed, a sheet and/or block of the disclosed polymericmaterial may function as a wedge-like structure when introduced betweenthe first and second elements in situ. In exemplary embodiments, thedisclosed polymeric material may be positioned and/or applied to the“male” portion(s) of the first and/or second elements of the disclosedinter-vertebral elements.

As described herein, the disclosed spinal implant assemblies may alsobenefit from movability of the first and second inter-vertebral elementsrelative to each other that is achieved clinically based on thestructural design and operation of the disclosed disc implant for alimited period of time. Exemplary disc implant assemblies of the presentdisclosure include a first inter-vertebral element having a first outerfusion surface and a first internal coupling surface, a secondinter-vertebral element having a second outer fusion surface and asecond internal coupling surface, a coupling means/mechanism for movablyconnecting/coupling the first and second inter vertebral elementsrelative to each other. In addition, each inter-vertebral elementgenerally includes one or more osseointegrative sectionsenabling/facilitating further fixation of the first and second elements.

Overview information related to shape, coupling means/mechanisms, size,material, coating, coating material, osseointegrativesection(s)/openings, incisions/circumferential inset regions, temporalmovability and methods of treatment associated with advantageous spinaldisc implant assemblies contemplated according to the present disclosureare described herein.

a. Shape

The disc implant according to the invention may have any shape thatenables transient stabilization and stimulates long term fixation byfusion and bone in-growth.

The shape of the disc implant, as seen from the top, may includegeometries such as a round, circular, oval, oblate or kidney shape. Thedisc implant may be designed for use in posterior or anterior surgery,but is preferably designed for use in anterior surgery, which may leadto a shorter recovery period after surgery. Alternatively, the disclosedimplant may be designed for transforaminal lumbar interbody fusion orlateral lumbar interbody fusion.

b. Size

The circumference of the disc implant may be smaller than thecircumference of the corpus. In particular, the geometry of thedisclosed spinal disc implant may be defined such that the basis of thecorpus protrudes relative to the implant at the front thereof. Forexample, the corpus may protrude at least 0.2 mm relative to theimplant, and optionally by as much as 0.4 mm or 0.6 mm past the edge ofthe implant. In further exemplary embodiments of the present disclosure,the distance from the outer edge of the implant to the edge of thecorpus is defined such that the distance is on the order of 5 mm orgreater.

Such dimensional arrangement may advantageously provide and/or permitstimulation of bone growth at or along the side of the disc implant and,following fixation of the inter-vertebral elements relative to adjacentvertebral bodies, bone tissue may join at or along the outer edges ofthe disclosed inter-vertebral elements, thereby further fixing theinter-vertebral elements relative to each other after a period of timepost-implantation.

c. Material

The disc implant assemblies according to the present invention may befabricated from any material(s) suitable for implantation. Thus, thedisclosed implant may be constructed from one or more materials selectedfrom, but not limited to, the group of ceramics, polymers, bone andmetals. Preferred are metals. polymers and ceramics. The material(s) maybe in states of glassy, rubbery, semi-crystalline, or crystalline,before and/or after processing into the implant.

In exemplary embodiments of the present disclosure, the disclosed spinalimplants may be constructed of metal or metal alloys selected from thegroup of, but not limited to, stainless steel, cobalt-chromium, titanium(Ti), titanium alloys, shape memory alloys, e.g., NiTi, tantalum (Ta),niobium (Nb), zirconium (Zr) and platinum (Pt). Preferred metals andmetal alloys are titanium, tantalum, titanium alloys, andcobalt-chromium and alloys thereof. Exemplary cobalt-chromium materialsfor use according to the present disclosure include CoCrMo alloys.Exemplary titanium alloys for use according to the present disclosureinclude Ti6Al4V. Exemplary stainless steel materials for use accordingto the present disclosure include austenitic stainless steels,especially types 316 and 316L, and Ni-free stainless steel.

Metals, such as transition metals, may be used to fabricate discimplants according to the present disclosure. For example, tantalum(Ta)—a corrosion-resistant material—may be employed. Indeed, tantalummay be useful for implant fabrication according to the presentdisclosure because it is generally immune to the action of body liquidsand is non-irritating. Titanium is a second transition metal that iscorrosion resistant, offers high stiffness and is physiologically inert,thereby enhancing its usefulness according to the present disclosure.Titanium and tantalum have the unusual ability to osseointegrate.Furthermore, the anatomical position of disc implants fabricated fromthese metals may be easily analyzed by conventional imaging methods.

Exemplary ceramic materials for use according to the present disclosureinclude, but are not limited to, bio-inert ceramics (alumina (Al₂O₃),partially stabilized zirconia (ZrO₂), silicon nitride (Si₃N₄), bioactiveceramics (hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) and bioglasses), andresorbable ceramics (e.g., calcium phosphate ceramics such astri-calcium phosphate, Ca₃(PO₄)₂). Apatite refers to a group ofphosphate minerals, usually referred to as hydroxylapatite,fluorapatite, and chlorapatite, named for high concentrations of OH—,F—, or Cl-ions, respectively, in the crystal lattice. Hydroxylapatite isthe major component of tooth enamel and a large component of bonematerial. Hydroxylapatite is a naturally occurring form of calciumapatite with the formula Ca₅(PO₄)₃(OH), but is usually writtenCa₁₀(PO₄)₆(OH)₂ to denote that the crystal unit cell comprises twomolecules. Hydroxylapaptite is easily accepted by the recipient andprovides substantial stimulation of bone in-growth.

Most of the calcium phosphate ceramics are crystalline substances. Thecrystals are subjected to heat treatment at high temperatures, andsintered to produce a bioceramic material. Chemically, they arehydroxyapatite, tricalcium phosphate, or mixtures of the two. They aregenerally supplied as powders, granules, or porous or non-porous blocks.

Tricalcium phosphate is more porous than hydroxyapatite, and isbiodegraded ten to twenty times faster. The sintering temperature alsohas an influence on the behavior of the finished product. Depending onmanufacturing conditions, tricalcium phosphate will be totally resorbedwithin a few months, or take several years to be removed bybioresorption. In the body, it is partially converted to hydroxyapatite,which is biodegraded more slowly. In exemplary embodiments of thepresent disclosure, artificial bone material is employed, such asresorbable ceramic granules and resorbable tricalcium phosphate (TCP)ceramic granules.

The disclosed spinal implant may further be fabricated, in whole or inpart, using glassy and pyrolytic carbon, which is highly efficient forstimulating bone fusion.

Exemplary polymers for use, in whole or in part, in fabricating spinalimplants according to the present disclosure may be selected from, butare not limited to, the group of polylactides (PLA), polyglycolides(PGA), polyanhydrides, polyorthoesters, poly(D,L-lactic acid),poly(lactide-co-glycolide) (PLGA), poly-D,L-lactic acid-poly(ethyleneglycol), polyphosphates, poly(2-hydroxy ethyl methacrylate),poly(N-vinyl pyrrolidone), poly(methyl methacrylate), poly(vinylalcohol), poly(acrylic acid), polyacrylamide, poly(ethylene-co-vinylacetate), poly(methacrylic acid), ultra high molecular weightpolyethylene (UHMWPE), polyether ether ketones (PEEK) and polyetherketone ketones (PEKK). Preferred polymers according to the presentdisclosure include PEEK and PEKK. According to exemplary embodiments, apolymeric element (e.g., sheet, block and/or surface treatment) may bepositioned between opposing metallic surfaces according to the presentdisclosure.

Exemplary bone for use, in whole or in part, in fabricating spinalimplants according to the present disclosure may be selected from thegroup of xenograft, allograft and autograft. Preferred bone according tothe present disclosure include xenograft and allograft.

The disclosed implant may be fabricated from one or more suitablematerials. Thus, in exemplary embodiments, the disclosed spinal implantis made of at least one of the materials mentioned above. In furtherembodiments, the disclosed implant is made of at least two differentmaterials. Either material may constitute such as between 1 and 90percent of the total volume of the entire implant. Thus, one materialmay constitute 1-10%, 10-20%, 20-30%, 30-40%, 40-50%, 50-60%, 60-70%,70-80% or 80-90% of the total volume of the entire implant. The elementsof the implant may comprise a central core of a metal surrounded by alayer of resorbable ceramic material. In further embodiments, thedisclosed implant is made of at least three different materials.

The resilience of the material of the disc implant is preferably of anorder similar to the resilience of bone. In addition, one or moreelements or part of elements may be covered by a coating layer of aparticular material in order to optimize function.

d. Coating

Coating of the implant can be performed to protect the implant from bodyfluids, including blood at the time of implantation as well as in aperiod followed implantation. A coating may alternatively or in additionbe used for controlling bone growth in the vicinity of the implant byincluding suitable compounds.

In exemplary embodiments, the disclosed implant may be coated on theouter fusion surface, the internal coupling surfaces or the internalsurface of the openings of the elements or any part of each surface orany combination of surfaces. In a preferred embodiment, the internalsurface of the openings is coated.

The coating generally includes at least one layer of a coating material.The coating material may be selected from any suitable material. Thus,the coating may include osteoinductive and/or osteogenic agent(s) asdescribed here below. The coating may also take the form of a suitablepolymeric material, e.g., a material that minimizes metal-to-metalcontact of the first and second inter-vertebral elements. The coatingmay further include one or more antibiotics.

By “coated” is meant that the coating material may be situated only onthe outside of the coated surface. The thickness of the coating isgenerally selected based on the desired function and properties of thecoating, and may have a thickness of less than 1 mm, less than 0.5 mm,or less than 0.25 mm. The thickness of the coating may also vary alongthe surface of the disclosed implant, e.g., at different surface pointsof the implant. The coating of the disclosed disc implants may beperformed by any suitable coating method, e.g., by dipping the elementsinto a solution of the coating material for a predetermined time. Thecoating material may also be sprayed onto the implant; anotherpossibility is to apply the said coating by brushing.

e. Coating Material

In exemplary embodiments of the present disclosure, one or moreprotective coatings may be provided on the disclosed spinal implants,the materials for such protective coating(s) being selected from, butnot limited to, the group of polylactides (PLA's), polyglycolides(PGA's), polyanhydrides, polyorthoesters, poly(D,L-lactic acid),poly(lacide-co-glycolide) (PLGA), poly-D,L-lactic acid-polyyethyleneglycol, polyphosphates, poly(lactide-co-glycolide) composited withgelatine sponge, poly(2-hydroxy ethyl methacrylate), poly(N-vinylpyrrolidone), ethylene vinyl acetate (EVA), poly(methyl methacrylate),poly(vinyl alcohol), poly(acrylic acid), polyacrylamide,poly(ethylene-co-vinyl acetate), poly(ethylene glycol), poly(methacrylicacid), Homopolymers of L-PLA and poly-caprolactone (PCL),poly(orthoesters), like poly(anhydrides) and pseudo-poly(amino acids).The disclosed polymeric materials may advantageously limit and/oreliminate metal-to-metal contact between first and secondinter-vertebral elements according to the present disclosure.

In further exemplary embodiments, the coating(s) may containbiologically active components, e.g. osteoinductive and/or osteogenicagent(s) (such as hydroxyapatite and/or tricalcium phosphate) orantibiotics. As examples, the inclusion of osteoinductive and/orosteogenic agents in the coating may induce early osteogenic processes,e.g., chemotaxis of specific cell classes, while the inclusion ofantibiotics may reduce or prevent microbial infection.

Osteoinductive and/or osteogenic agents—which also can be denoted asand/or include “growth factors”—are generally proteins that bind toreceptors on the cell surface, with the primary result of activatingcell migration, cellular proliferation and/or differentiation. Manyosteoinductive and/or osteogenic agents are quite versatile, stimulatingcellular division in numerous different cell types, while others arespecific to a particular cell-type.

Materials that are considered osteoinductive generally containmorphogens, such as bone morphogenetic proteins. Morphogens initiatetissue and organ system development by stimulating undifferentiatedcells to convert phenotypically. Suitable growth factors which may beused according to the present disclosure include, but are not limitedto, tissue growth enhancing substances, such as growth anddifferentiation factors, that include platelet-derived growth factor(PDGF), transforming growth factor (TGF), acidic and basic fibroblastgrowth factor (FGF), insulin-like growth factor (IGF), bonemorphogenetic proteins (BMPs) and combinations thereof.

In exemplary embodiments of the present disclosure, the osteoinductiveand/or osteogenic agent may be selected from the group of bone growthfactors: platelet-derived growth factor (PDGF) (PDGF-AA, -AB, -BB),insulin-like growth factors I and II (IGF-I, IGF-II), fibroblast growthfactors (FGFs) (acidic FGF-aFGF, basic FGF-bFGF), transforming growthfactor beta (TGF-B) (TGF-B (TGF-Bs 1, 2, 3, 4, and 5)), osteoinductionand bone morphogenetic protein (BMP) (BMP-1, BMP-2, BMP-3, BMP-4, BMP-5,BMP-6, BMP-7, BMP-8, BMP-9, BMP-10, BMP-11, BMP-12), epidermal growthfactor (EGF), cementum-derived growth factor (CGF), parathyroidhormone-related protein (PTHrP). Preferred growth factors orosteoinductive and/or osteogenic agents include the bone morphogeneticproteins (BMP-1, BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7, BMP-8, BMP-9,BMP-10, BMP-11, BMP-12) and platelet-derived growth factors (PDGF)(PDGF-AA, -AB, -BB).

Coatings for use according to the present disclosure may include atleast one osteoinductive and/or osteogenic agent, and optionally morethan one such agent, e.g., 2 agents, 3 agents, 4 agents, 5 agents, 6agents, 7 agents, 8 agents, 9 agents, 10 agents or more. Exemplaryimplementations of the present disclosure include 1, 2 or 3osteoinductive and/or osteogenic agents. More preferred implementationsinclude 1 or 2 osteoinductive and/or osteogenic agents.

One or more layers of the coating material may be placed on or appliedto the disclosed implant. In implementations where two or more layersare placed/applied, these layers may be equal or different incomposition and one or more layers may contain osteoinductive and/orosteogenic agent(s) or other biologically active components.

Alternatively, the osteoinductive and/or osteogenic agents may becomprised of one or more of the materials forming the elements of thedisclosed disc implant. Thus, the implant may be designed for secretionof one or more of the osteoinductive and/or osteogenic agents, wherebystimulation of bone growth is directed by or otherwiseinitiated/supported by the elements of the disc implant. The discloseddisc implant preferably encourages bone formation.

f. Osseointegrative Section(s)/Opening(s)

The first and second inter-vertebral elements of the disclosed discimplants generally include and/or define osseointegrative sections. Suchsections generally have a capacity for stimulating and directing bonegrowth. For example, the inter-vertebral elements may be adapted tostimulate bone growth for fusion of the outer surface of each suchinter-vertebral element relative to the neighboring vertebralelement(s). The disclosed inter-vertebral elements are also generallyadapted to further direct bone in-growth for fixation of theinter-vertebral elements relative to each other.

The inner and outer surface of the first and second inter-vertebralelements may include and/or define osseointegrative sections designedfor optimization of bone in-growth according to the present disclosure.As described here below, the osseointegrative sections may be defined,in whole or in part, by openings, such as holes and/or incisions in thesurface of the inter-vertebral elements which provide entry points forbone in-growth. The osseointegrative sections may also include suitableosteoinductive and/or osteogenic agents, and/or osteoinductive and/orosteogenic materials. Implementations of the present disclosure whereopenings formed in the intervertebral elements include osteoinductiveand/or osteogenic agents, and/or osteoinductive and/or osteogenicmaterials within such openings are referred to as “filled” openings.

In exemplary embodiments of the present disclosure, the disclosedinter-vertebral elements include or define one or more openings suitablefor bone in-growth, such openings being sufficiently large to (i) allowentrance of osteoblasts and osteogenic cells and (ii) sustain theviability of such osteoblasts and osteogenic cells. The openingsgenerally proceed or extend through the disclosed inter-vertebralelements and allow in-growth of bone through the elements. The openingsmay have any shape or size compatible with the design/geometry of theinter-vertebral elements of the disc implant. For example, the openingsmay constitute or define straight (or substantially straight) channelsthat extend through the inter-vertebral element(s). In exemplaryembodiments, the diameter(s) of the opening(s) may vary as the channelextends through the inter-vertebral element, e.g., the diameter of theopening channels may be expanded with an internal void in the element.

The surface area of the intervertebral elements occupied by the openingsis generally sufficient to support desired levels of bone in-growth toachieve fixation of the first and second intervertebral elementsrelative to each other over time. However, it is noted that such bonein-growth is generally not limited to bone growth through such openings,but is complemented by bone in-growth that extends along or around theouter edges of the inter-vertebral elements. In exemplary embodiments ofthe present disclosure, the openings occupy at least 5% of the surfacearea of the first and/or second intervertebral element(s), and infurther exemplary embodiments, at least 10% or at least 15% of suchsurface are in order to permit/stimulate sufficient in-growth of bone.In further exemplary embodiments, the surface area of the first and/orsecond inter-vertebral element(s) that is occupied by the openings/holesis 10-40% of such surface area, e.g., 20-35% thereof. The openings andthe internal void volume may constitute 10-90% of the bulk volume of theinter-vertebral elements of the disclosed disc implants, e.g., 20-80%,30-70%, 40-60% and/or 30-60% of the bulk volume of the inter-vertebralelements.

When referring to the bulk volume of the inter-vertebral elements, thevolume of the coupling zone is not included, but merely the approximatevolume of the individual inter-vertebral elements, including the volumeof the openings and internal void volume, if present.

In exemplary embodiments of the present disclosure, the one or moreopenings of the first and second inter-vertebral elements are opposingeach other, i.e., substantially aligned, when the inter-vertebralelements are engaged with each other via the coupling means/mechanism.An opposed/aligned arrangement of such openings provides optimalconditions for promoting bone in-growth though both inter-vertebralelements to achieve desired objects of the present disclosure, e.g.,fusion of the disc implant at each outer surface relative to adjacentvertebral bodies and fixation of the first and second inter-vertebralelements of the disc implant elements relative to each other when bonetissue is formed in the coupling zone formed/defined by the internalsurfaces of the inter-vertebral elements.

Minor openings on the surface of one or both inter-vertebral elementsmay be denoted as “pores”, which affect the capabilities of the implantto stimulate bone growth at the surfaces. The level of porosity, poresize distribution, pore morphology, and the degree of poreinterconnectivity of implants significantly influences the extent ofbone growth. An exemplary pore volume on the outer surface of the firstand/or second inter-vertebral body to encourage osteoinduction is150-500 mm3. In addition, the outer surfaces of one or bothinter-vertebral elements may further be rough, rugged or granular tofurther promote fusion relative to adjacent vertebral bodies.

g. Incisions/Circumferential Inset Regions

Alternative to or in combination with openings as described above, thedisclosed inter-vertebral element(s) may include or define incisions orcircumferential inset regions of various shapes/geometries to facilitatebone in-growth and fixation of the first and second inter-vertebralelements over time. Thus, in exemplary embodiments of the presentdisclosure, openings in and through the intervertebral elements may becombined with incisions/circumferential inset regions topromote/facilitate desired levels of bone in-growth. For example, thedisclosed openings and incisions/circumferential inset regions maystimulate osteoconduction by providing a scaffold for the cells to moveinto and create new bone.

As noted above, the inter-vertebral elements of the disclosed discimplant may be fabricated from one or more different materials. Inexemplary embodiments of the present disclosure, a filling may belocated in the openings and/or incisions/circumferential inset regionsof the intervertebral elements of the disc implant, whereby a filledimplant is obtained. The filling may include material(s) suitable fordirecting and/or stimulating osteogenic activity and or inhibition ofbone resorption. For example, auto and/or allograft of bone ordemineralized bone matrix (DBM) may be used as a filling material.Artificial bone materials, such as ceramic materials, may also beemployed. Resorbable materials, such as resorbable ceramic granules, mayalso be utilized, allowing and/or facilitating bone formation in theopenings and/or incisions/circumferential inset regions within asuitable time. Thus, the disclosed spinal implant may be filled withresorbable materials, such as resorbable ceramic granules, which bysuitable packaging may aid in the timing and/or extent of bonein-growth. In further exemplary embodiments, the filling may includeosteoinductive and/or osteogenic agent(s), as described in relation tocoatings.

h. Fusion of Implant

The spinal disc implant according to the present disclosureadvantageously fuses with the surrounding vertebrae. In particular, theouter fusion surface of the first and second inter-vertebral elementsare suited for fusion with neighboring bones/vertebral bodies. Theelements of the disclosed disc implant are constructed to stimulateosteoconduction, i.e., the channeling of bone growth through theinter-vertebral elements of the implant. This bone in-growth leads tofixation of the first and second inter-vertebral elements relative toeach other. In an exemplary embodiment of the present disclosure,fixation of the first and second inter-vertebral elements relative toeach other—leading to the formation of a fixed implant—is caused atleast in part by bone in-growth which occurs predominantly through theosseointegrative section(s) of the inter-vertebral elements of the discimplant.

i. Methods of Treatment

An individual suffering from lower back pain and/or leg pain resultingfrom spine injury or other disease may obtain relief by an insertion ofa disc implant. An aspect of the present disclosure relates to method(s)of treatment of an individual in need thereof, wherein the methodincludes insertion of a disc implant. The disclosed method(s) may beachieved through anterior, lateral, posterior and or transforaminalinsertion. In addition, the disclosed method(s) may be combined withinsertion/implantation (or pre-existing) posterior stabilizationmeans/devices. The posterior stabilization can be in form of flexible(dynamic), semi-rigid or rigid implants, such as pedicle screws,interspinous process spacers or facet joint screws or any otherfixation/stabilization method known or subsequently developed in theart.

The first and second inter-vertebral elements may be introducedsimultaneously, i.e., in a “pre-assembled” configuration. Alternatively,the first and second inter-vertebral elements may be introducedsequentially, with side-by-side assembly/positioning of the first andsecond inter-vertebral elements being undertaken and/or achieved insitu. To the extent a third element, e.g., a polymeric sheet or block,is positioned between the first and second inter-vertebral elements,such intermediate third element may be positioned relative to the firstand/or second inter-vertebral element prior to anatomical positioning ofthe implant in the desired spinal location, or may be introducedsequentially, e.g., after the first and/or second inter-vertebralelement is introduced to the anatomical location.

Although the present disclosure has been described with reference toexemplary embodiments thereof, the present disclosure is not limited byor to such exemplary embodiments. Rather, various modifications,refinements and/or changes may be made with reference to the spinalplates disclosed herein without departing from the spirit or scopethereof. For example, as one skilled in the art would immediatelyappreciate from the present disclosure, with the mating of the top andbottom elements as described, a variety of top and bottom elements couldbe designed and provided. For example, the length of the plates could bevaried, as well as the number of screw holes. These variations wouldenable treatment of different anatomical sizes. The present disclosureexpressly encompasses these and other modifications, refinements and/orchanges, as will be apparent to persons skilled in the art.

1. A spinal plate, comprising: a. first and second elements that definespaced sheets that are configured and dimensioned to interleave relativeto each other; and b. a fastening mechanism for fixing the first andsecond elements relative to each other.
 2. The spinal plate according toclaim 1, wherein the first and second elements define arcuategeometries.
 3. The spinal plate according to claim 1, wherein thefastening mechanism includes apertures that extend at least in partthrough at least one of the first and second elements.
 4. The spinalplate according to claim 3, wherein the fastening mechanism furtherincludes a fastening member adapted to fix the first element relative tothe second element.
 5. The spinal plate according to claim 1, furthercomprising one or more structural elements that are adapted tofacilitate connection of the spinal plate relative to an implant.
 6. Incombination, a spinal plate according to claim 1 and an implantconnected relative thereto.
 7. The combination according to claim 6,wherein the spinal plate is connected relative to the implant prior toimplantation.
 8. An implant assembly, comprising: a. a superior implantelement that includes an upstanding flange and a first intervertebralelement extending from the upstanding flange, wherein the superiorimplant element further defines (i) an opening bounded by first andsecond arcuate boundary walls, and (ii) an opening formed in theupstanding flange for receipt of a locking member; and b. an inferiorimplant element that includes a flange portion and a secondintervertebral element extending from the flange portion, wherein thesecond intervertebral element further includes an upstanding tab thatdefines at least one arcuate face and that is configured and dimensionedfor receipt in the opening of the superior implant element that isdefined by first and second boundary walls.
 9. The implant assemblyaccording to claim 8, wherein the upstanding tab defines opposed arcuatefaces.
 10. The implant assembly according to claim 8, wherein theupstanding tab is interleaved between the first and second boundarywalls when the superior implant element is assembled with respect to theinferior implant element.
 11. The implant assembly according to claim 8,wherein the upstanding tab of the inferior implant element and theopening bounded by first and second arcuate boundary walls of thesuperior implant element accommodate flexion/extension rotationalfreedom of movement as between the inferior implant element and thesuperior implant element until such time as the superior implant elementand the inferior implant element are fixed relative to each other. 12.The implant assembly according to claim 8, wherein the upstanding flangeand the flange portion include cooperating arcuate faces.
 13. Theimplant assembly according to claim 8, wherein the upstanding flangeincludes at least one aperture to facilitate mounting of the superiorimplant element relative to an anatomical structure.
 14. The implantassembly according to claim 8, wherein the flange portion includes atleast one aperture to facilitate mounting of the inferior implantelement relative to an anatomical structure.
 15. The implant assemblyaccording to claim 8, wherein the opening formed in the upstandingflange for receipt of a locking member is threaded.
 16. The implantassembly according to claim 8, further comprising a locking memberconfigured and dimensioned for cooperation with the opening formed inthe upstanding flange for receipt of a locking member.
 17. The implantassembly according to claim 8, wherein the first intervertebral elementand second intervertebral element include openings that permit boneingrowth.